Ensuring one number is a whole number greater than the other

[key]

Hi, im trying to sort a little spreadsheet out for my work and have come to a dead end with this problem. I have two figures, (i.e. 3.5 & 5) but i need to make the difference between the two figures a whole number, (i.e. 1or 2 or 3). So i would have to change the 3.5 - 5 to 3.5 - 5.5.
eg

2.5 - 4.5 ok
1.5 - 4 1.5 - 4.5
4.5 - 6 4.5 - 6.5
3 - 4 ok

I think i need to use the =mod function but can't get my head around the equation needed.

Any help much appreciated

Regards
Key

[daddylonglegs]

It's easier if you have the values in separate cells so say you have the lower value in A2 and the higher in B2, i.e. 3.5 in A2 and 5 in B2, then this formula in C2 will give the value that B2 needs to be so that the difference is an integer

=CEILING(B2-A2,1)+A2

[shg]

Or =A2 + ROUND(B2-A2, 0)

The formulas will give different results depending on the inputs ...

[key]

Thanks guys, ended up using Daddylonglegs's equation within mine, I had to round up the answer to the nearest half and then ensure it was a whole number greater than D3

=(CEILING(CEILING(S3/U3, 0.5)-D3,1)+D3)

not sure I needed both ceiling functions but the end result was the correct one so thanks for all your help.
Regards

Key